Improvement in tanning



. UNITED STATES PATENT OFFICE.

HARRIS STRATTON, JR., OF LEAVENWORTH, KANSAS.

IMPROVEMENT IN TANNING.

To all whom it may concern:

Be it known that I, HARRIS STRATTON, J r., of the city and county of Leavenworth, and State of Kansas, have invented a new and Improved Process for Tanning; and I do hereby declare the following to be a full and exact description of the same.

This invention consists, first, in more cifectual and expeditious means for softening and depilatin g the hides preparatory to submitting them to the tanning process; second, in the employment of a novel tanning compound, whereby leather of a superior quality may be produced in an economical manner and in greatly reduced time, all as will be hereinafter fully explained.

In order thatothers skilled in the art to which my invention appertains may be enabled to fully understand and use the same, I will proceed to describe the manner of carrying itinto efi'ect.

To soften and unhair the skins or hides I employ a medium consisting of water impreg-' nated with sulphate'of soda and fresh-slacked .lime. The proportion in which these ingredi cuts are used is about three parts of soda to one part of lime. In practice, when a new solution is to be made, take, for example, one hundred and fifty pounds of soda and dissolve the same in water, with which a depilating-vat of ordinary size may be filled. Fifty pounds of fresh-slaked lime is then added, after which the whole is thoroughly stirred until the water is effectually impregnated. The hides, having been previously soaked for a few hours, are spread evenly in this solution, the hair side beingplaced upward. The handling is performed twice each day, and the hides are left in retreat for one hour at every operation. The time required by this process to plump or distend and unhair the hides will be from two to four days. This solution not only plumps and unhairs the skins, but softens the most obdurate flint-hide without previously breaking the same. The sulphate of soda, by its almost instantaneous action on the hide, prevents the lime from destroying the'albumen or fibrine' contained therein, and thus eifects a saving of much weight. By the above means the hides may be prepared for the tanning process in y from ten to twenty days less time than by the modes hitherto devised.

My improved tanning process may be described as follows: For a pack of hides consisting of one hundred calf-skins I employ a tanning compound constitued as follows: one hundred pounds terra-japonica; one hundred pounds Sicilian sumac, (or two hundred pounds of native white sumac;) twenty-five pounds sulphate of soda; three to five pounds nitrate of potassa; two hundred pounds bois darc bark, (Osage orange.)

To prepare the solution the sumac is first boiled for thirty minutes in one or two hundred gallons of water, which is then allowed to settle and passed into a vat The sulphate of soda and nitrate of potassa are then'dissolved in cold water and poured into the vat, after which a suficient quantity of cold. water may be added to reduce to 60 the temperature of the solution contained within the vat, and the whole is thoroughly stirred. The skins are then taken from the bait, and, being first well worked on the grain side, are spread, grain side up, in the liquid in the vat. The handling maybe performed every hour the first day. As soon as the grain is well set and colorecl (which takes two or three days) steep ten pounds of terra-japonica and twenty pounds of bark (boisdarc, bow-wood) for thirty minutes, and add this amount daily until the skins are tanned, which tanning will be effectually accomplished in about ten days. Where the bois darc bark cannot be easily procured the quantity of japonica may be doubled, and if the japonica cannot be easily obtained use three times the quantity of bark. For treating heavier stock than that above mentioned it is only necessary to increase the quantity ofjjaponica and bark. Sole-leather, as it becomes nearly filled, requires from two to four pounds ni'ore nitrate of potassa to solidify it and close the pores.

The tanner, by using the above process, has the entire stock under his full control at all times.

If the skins or hides are not suffioiently plump, the addition ofa few pounds of sulphate of soda will produce the desired effect. If too plump or distended, the addition of from two to four pounds of nitrate of potassa will pro duce the desired solidification. If the color be too dark, add to the sumac; if too light, add to the japonica.

Oak-bark or other tanning substances may be substituted for the japonica, if desired.

In order to effect the more rapid absorption of the tannin, I keep the solution, after the second day, at a temperature of from 85 to 96 The time required to tan the different varieties of leather by the above process is as follows: calf and other light skins, ten days;

'light kip, eighteen days; heavy kip, twentyfive days; upper-leather, thirty days; bridleleather, thirty-five to forty days harness-leather, forty to fifty days; skirting-leather, fifty to sixty days; sole-leather, sixty days.

It has been found that leather tanned as above is soft and pliant and never becomes harsh; and, moreover, that it is very durable and tough, and also preserved from cracking. Leather thus tanned will take one-third more stuffing than that tanned by oak-bark, which is a very importautanvantage where the leather is sold by the pound. g

The importance of this compound for tanning will at once be seen when the fact is taken into consideration that in the vicinity of prairies and in many other localities no oak or hemlock bark can be procured; and in many timbered districts the timber has become so valuable that it is not desirable or judicious to destroy the same merely for the purpose of obtaining the bark. Another desideratum is that in most localities where tanning is extensively carried on the bois darc tree grows in great abundance, the bark of the tree being a most valuable accessory as a tanning agent.

In Kansas,Nebraska, and other States where leatherisextensivelymanut'actured,largequantities of the white sumac can be procured at a mere nominal price.

The sulphate ofsodaplumps the skins quickly and without the deleterious effects which are produced by the use of sulphuric acid.

The nitrate of potassa is a natural preservative of animal fibrine and gelatine, and assists materially in driving the tannin through the SKIDS.

Having thus described my invention, the following is what I claim as new therein and desire to secure by Letters Patent:

1. A tanning compound constituted of terrajaponica, Sicilian or native sumac, sulphate of soda, nitrate ot potassa, and bois da-rc (bew- Wood) bark, the Whole being combined and employed in the manner herein specified.

2. The combination of sulphate of soda and lime, employed in the manner described, for softening and unhairing the hides preparatory to tanning.

The above specification of my improved process for tanning signed this 10th day of February, A. D. 1864.

HARRIS STRATTON, JR. [L. s.]

Witnesses SAMUEL F. A'rwoon, W. W. OnnIGH'roN. 

